1. Field of the Invention
The present invention is directed to the field of textile laundering, to cyclodextrin compositions containing textile laundering additives for use therein, and to processes for producing these compositions.
2. Background Art
Textiles are subjected to laundering during several stages in their life cycles. For example, textiles may be laundered after weaving to remove traces of spin finishes and/or lubricants applied during yarn preparation or prior to weaving, to remove soil accumulated during the weaving process, to remove fugitive dyes, etc. Textiles may also be laundered prior to fabrication into articles such as white goods, clothing, etc., or following fabrication, to impart fabric finishes such as softeners, antistats, or brighteners, to modify the appearance, e.g. stone washing, partial bleaching, etc. The term “laundering” and like terms as used herein apply to all these activities and to others whereby textiles are contacted with aqueous detergent-containing compositions to alter their properties.
Many laundering compositions have been developed for the above uses, the vast majority in relatively concentrated form, which are diluted upon use to form an aqueous working composition of the desired strength. Non-limiting examples of such compositions include liquid and dry laundry detergents, fabric softeners, bleaches, particularly non-chlorinated bleaches, rinse aids, optical brigheners, etc. Frequently, compositions are marketed which perform several of the functions of the compositions identified above in a single composition. Thus, laundry detergents frequently include oxygen bleaches, optical brighteners, fabric softeners, antistatic agents, and UV absorbing materials. Incorporation of these components into a single composition is particularly important for the ultimate consumer, who is not likely to wish to add a variety of different products to a wash load, particularly at different times in the wash cycle.
Typical laundering processes, whether domestic or industrial, require several cycles, e.g. one or more treatment cycles followed by one or more rinse cycles. In many cases, it is necessary that a desired active component be effective over several or all of these cycles, and at times, to be highly effective during the latter of the cycles. In the case of antifoams, for example, it is desirable that these retain their efficiency during the wash cycles and also desirably at least the first rinse cycle.
The majority of components of laundry compositions are water soluble. These include, for example, the detergents, whether ionic, nonionic, or zwitterionic, the builders and sequestrants, alkalizers, salts, etc. Other ingredients such as antifoams, softeners, rinse aids, and optical brighteners may be only partially soluble or insoluble. Still other active ingredients may be soluble, but it is desired that are released and deposit on the textiles later in the wash process so that the deposits remain on the textile even after the rinse cycle is complete. The active ingredients must also be storage stable in their respective compositions, i.e., concentrates such as granulated or liquid laundry detergents. However, many detergent actives do not exhibit such stability.
In the case of antifoams, for example, simple silicone oils are known as effective antifoam agents. However, their antifoam activity diminishes rapidly during even a first wash cycle, and hence quite complex formulations including silicone oils, silicone resins, and other additives, frequently adsorbed or absorbed onto or into porous supports such as fumed or precipitated silica have been developed. Even so, many of these compositions are not storage stable in some compositions, particularly liquid detergents, and thus special formulations have been developed for these products. In the case of softeners, brighteners, antistats and the like, which must remain on the laundered fabric, it is desirable that these ingredients are efficiently deposited and remain adherent, as components which exit during the wash or rinse cycles represent a loss of active ingredient which then requires an increased amount in the composition to be effective for their intended purpose.
Cyclodextrins are cyclic molecules of linked saccharides. The most common cyclodextrins (“CDs”) are α-CD, β-CD, and γ-CD, containing 6, 7, and 8 D-glucopyranosyl moieties, respectively. These cyclodextrins have limited water solubility, β-CD having a water solubility of only about 18 g/L, while α-CD and γ-CD have somewhat higher solubilities, 145 and 232 g/L, respectively. Cyclodextrins may be modified, to produce alkyl-, hydroxyalkyl-, ester- and other modified CDs. CDs have a relatively hydrophobic guest cavity and a hydrophilic exterior, and have been used, e.g. to form inclusion complexes of odiferous and/or easily oxidizable polyunsaturated oils, as in U.S. Pat. Nos. 4,775,749; 4,777,162; 4,831,022; and 5,189,149. The odor of such products is reduced considerably and their oxidative stability enhanced. Inclusion of flavor oils, for somewhat the same reasons, is disclosed in U.S. Pat. No. 6,287,603. The foregoing products are, in general, used in powder form.
CDs have also been shown to be useful in supplying relatively water-insoluble drug candidates at higher concentrations than the aqueous solubilities of the dry actives, as disclosed in U.S. Pat. No. 6,432,928, wherein CDs whose water solubility has been increased by modification are used to complex the poorly soluble pharmaceutical actives.
The ability to form inclusion complexes is necessarily limited to molecules which can enter the hydrophobic cavity. Furthermore, the usefulness of CD inclusion complexes is unpredictable when the chemistry of the surroundings is complex. For example, inclusion complexes of ω-3 fatty acids, when dispersed in oily vehicles, can exhibit guest/solvent interchange, and thus the benefits of including the ω-3 fatty acid in the CD complex are largely lost.
CDs have seen only limited use in laundering compositions. For example, in DE 4 035 378, fabrics are treated with cyclodextrins which are then linked to the fabric by use of traditional cellulose-reactive crosslinkers. The fabric, now bearing cyclodextrin groups on its surface, is rendered odor-resistant, the cyclodextrins absorbing odiferous molecules during wearing by the user. Athletic socks with the aforementioned bonded cyclodextrin having experienced some commercial success.
In EP 1127940, detergents useful for washing textiles to produce a textile product with soft hand are disclosed. The soft hand is said to be imparted by interaction of the CD with the fabric. In addition to the CD, the formulations contain a long chain aliphatic carboxylic acid, and a cationic surfactant. However, no CD inclusion complexes are disclosed. Because of the high loadings of powerful surfactants, alkali, builders, sequestrants and the like, it would not be expected that CD inclusion complexes would be useful in laundering compositions. This is especially the case when the composition also contains quantities of hydrophobic substances, which would be expected to exchange with the guest of a CD guest/host inclusion complex.